JPH03288326A - Magnetic recording medium and production thereof - Google Patents

Abstract

PURPOSE:To decrease drop-outs and to suppress head wear by incorporating a higher fatty ester of carbon atoms of a specific value or above into a magnetic layer and subjecting the magnetic layer to a surface treatment with a super hard material. CONSTITUTION:The magnetic layer of the magnetic recording medium formed by providing the magnetic layer on a nonmagnetic base contains the higher fatty ester of >=24C and is subjected to the surface treatment with the super hard material. This magnetic recording medium is produced by the method of incorporating or not incorporating the higher fatty ester of >=24C during and/or after forming the magnetic layer on the nonmagnetic base, then subjecting the surface of the magnetic layer to the surface treatment with the super hard material. The higher fatty acid is otherwise incorporated into the magnetic layer after the surface treatment.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording medium having a magnetic layer provided on a non-magnetic support and a method for manufacturing the same, and particularly relates to a magnetic recording medium having a magnetic layer provided on a non-magnetic support and a method for manufacturing the same. The present invention relates to a recording medium and its manufacturing method.

[Conventional technology and its problems]

Recently, as devices such as VTRs have become more widespread and film-based, there has been an increasing demand for higher performance and higher recording characteristics in magnetic recording media.1. As a countermeasure, improvements in various materials, such as improvements in ferromagnetic powders and binders, improvements in additives such as abrasives, lubricants, and antistatic agents, and improvements in manufacturing methods, such as kneading methods, Improvements have been made in coating methods, surface treatment methods, etc.

In particular, it is known that the durability of the magnetic layer and the wear of the magnetic head can be reduced by lubricating the surface of the magnetic layer.

In addition, the magnetic layer is not limited to the magnetic layer of a coated magnetic recording medium formed by coating a magnetic paint in which a binder, ferromagnetic powder, additives, etc. are dispersed in a solvent on a non-magnetic support. A metal thin film provided thereon by vapor deposition or the like may also be used, and ferromagnetic thin film magnetic recording media having such a metal thin film are also being developed as next-generation media.

As means for utilizing this lubricant, there are known methods such as adding the lubricant to the magnetic layer coating liquid, or coating the surface of the magnetic layer with the lubricant.

Conventionally, mineral oils, silicone oils, higher alcohols, higher fatty acids, fatty acid esters, beef tallow, whale oil, animal oils such as whale oil, or vegetable oils have been used as lubricants.

For example, in Japanese Patent Publication No. 41-18065, carbon number 2 to 1
0.5 to 2 fatty acid esters consisting of up to 8 monobasic fatty acids (excluding carbons in the carboxyl group) and monohydric alcohols having 14 or more carbon atoms per 100 parts by weight of the binder.
The same magnetic recording medium formed by adding 0 parts by weight was published in Japanese Unexamined Patent Publication No. 5
4-124716 discloses an abrasive having a Mohs hardness of 6 or more, n-butyl stearate, dodecyl stearate,
A coated magnetic recording medium having a higher fatty acid ester such as propyl palmitate is described in Japanese Patent No. 55-157131. JP-A-59-186130 discloses a coated magnetic recording medium containing isocetyl stearate, which is said to be effective in improving the durability of the magnetic layer and suppressing head wear.

Furthermore, U.S. Pat. No. 4,303,738 also discloses a coated magnetic recording medium using tridecyl stearate,
The durability of the tape is superior to esters such as butoxyethyl stearate and isocetyl stearate;
It is also described that head abrasion is improved.

It is not possible to simply compare which of the lubricants disclosed in the above documents is the best lubricant. This is because the composition systems of the magnetic layers that hold the lubricant are different.

However, when it comes to boat fishing and magnetic recording media in general, increasing the amount of these lubricants usually increases the lubrication effect, suppresses head wear, and improves electromagnetic conversion characteristics, but at the same time reduces the mechanical strength of the magnetic coating. becomes weaker, reducing the durability of the paint film and increasing dropouts. Also, conversely,
Using less lubricant will reduce dropouts, but
There was a problem in that head wear was accelerated and electromagnetic conversion characteristics deteriorated.

On the other hand, as a measure to improve the durability of the magnetic layer, methods have been proposed and implemented, for example, adding non-magnetic inorganic powder such as abrasives (hard particles) to the magnetic layer; Otherwise, the effect of the addition will not be apparent, and head wear may have to be sacrificed, head clogging may occur more easily due to detachment or abrasion of the abrasive, and dropouts may occur more easily due to protrusions on the surface of the magnetic layer. Therefore, in order to eliminate these adverse effects caused by the surface properties of the magnetic layer, various surface treatment methods are applied to the surface of the magnetic layer to improve the surface properties of the magnetic layer surface. Measures have been taken to do so.

For example, Japanese Patent Application Laid-open No. 1-201824 discloses that the surface of a magnetic layer of a coated magnetic recording medium containing α-alumina as an abrasive and butyl stearate as a lubricant is polished to a mirror finish using a spark calender. The company discloses a method of polishing using a hard polishing wheel, which it claims reduces dropouts and improves skew fluctuations.

Furthermore, in Japanese Patent Application Laid-Open No. 2-23521, the surface of the magnetic layer of a coated magnetic recording medium containing the same abrasive and lubricant as in the above publication is mirror-finished, and then polished with a high-hardness material such as diamond. The company discloses a method of polishing with a wheel, which it claims reduces dropout, improves steel, reduces head wear, and improves magnetic layer damage.

Furthermore, as described in Japanese Patent Application Laid-Open No. 63-259830, the present applicant similarly applied a mirror polishing treatment to the magnetic layer of a magnetic recording medium containing the same abrasive and lubricant as described above using a spark calender, and then We have attempted to improve the durability of the magnetic layer, reduce dropouts, and improve head clogging by polishing with an abrasive tape and, if necessary, grinding with a high-hardness blade or rotating blade. .

However, in the magnetic recording medium manufactured in this manner, a problem has arisen in that the electromagnetic conversion characteristics, particularly the Y S/N, deteriorate.

Therefore, if we had to develop a new lubricant or a new adhesive in order to solve this problem, it would be difficult to provide magnetic recording media at a low price. ) and 1/).

In other words, it is ultimately difficult to obtain durability of the magnetic layer using conventionally known lubricants without sacrificing electromagnetic characteristics and head abrasion properties.

Therefore, the present inventor made surface treatment of the magnetic layer essential.
We believe that if a superhard material is used in this process, the adverse effects caused by surface properties can be improved to some extent even if other factors are ignored, and we reiterate that the most necessary element for processing this superhard material is a lubricant. The present invention was discovered as a result of recognizing this, reconsidering the selection of lubricants as a dependent element, and conducting intensive studies, and is not simply a combination of known techniques.

[Purpose of the invention]

That is, an object of the present invention is to provide a magnetic recording medium with good YS/N characteristics that reduces dropout and suppresses and improves head wear.

[Means to solve the problem]

An object of the present invention is to provide a magnetic recording medium having a magnetic layer provided on a non-magnetic support, wherein the magnetic layer contains a higher fatty acid ester having 24 or more carbon atoms, and is surface-treated with a superhard material. A method for producing a magnetic recording medium comprising a magnetic layer and a magnetic layer on a non-magnetic support, during and/or after the formation of the magnetic layer on the non-magnetic support. , after containing or not containing a higher fatty acid ester having 24 or more carbon atoms,
This is achieved by a method for producing a magnetic recording medium, which is characterized in that the surface of the magnetic layer is treated with a superhard material, or that the higher fatty acid ester is contained in the magnetic layer after the surface treatment.

The present invention provides a magnetic layer obtained by containing an appropriate amount of a higher fatty acid ester having 24 or more carbon atoms (hereinafter referred to as the compound of the present invention) in a magnetic layer and surface-treating the magnetic layer with a superhard material. The physical properties of the compound, such as surface roughness and surface free energy, are in harmony with the unique lubricating properties of the compound of the present invention. It is presumed that this reduces 2-build-out and suppresses head wear, thereby improving YS/N. That is, the surface treatment using a superhard material in the present invention can only be achieved by selecting the compound of the present invention from among known lubricants.

In the present invention, the expression "containing the compound of the present invention in the magnetic layer" includes the presence of the compound of the present invention only inside the magnetic layer, only on the surface, only at the slit ends, and/or in both or all of them.

The treatment of the magnetic layer using a superhard material carried out in the present invention may be carried out after or before the compound of the present invention is incorporated into the magnetic layer, or may be carried out both.

In the present invention, a magnetic recording medium having a magnetic layer to which the compound of the present invention can be applied is typically prepared by dissolving a binder such as a resin together with a ferromagnetic powder in an organic solvent and coating the mixture on a non-magnetic support. (hereinafter abbreviated as coated magnetic recording media), and media in which a magnetic layer is formed by vapor deposition or the like on a non-magnetic support (hereinafter abbreviated as metal thin film magnetic recording media). ), but as the metal thin film, those known in the industry can be used, and are not particularly limited, including those whose surface has been physically or chemically treated.

In the present invention, a nonmagnetic layer (hereinafter referred to as a back layer) can be provided on the other surface of the nonmagnetic support provided with the magnetic layer of both types of magnetic recording media. In particular, the present invention is effective in reducing dropout when a back layer is provided.

Methods for incorporating the compound of the present invention into the magnetic layer include a method of adding it into the magnetic layer, a method of topcoating the surface (a method of dissolving the compound of the present invention in an organic solvent, coating or spraying it on a substrate, and then drying it; (by melting the compound of the present invention and applying it to the substrate, by immersing the substrate in a solution of the compound of the present invention dissolved in an organic solvent and adsorbing the material to the substrate surface, by the Langmuir-Prodgett method, etc.) There are methods, methods using both of them, etc.

The amount of the compound of the present invention added to the coated magnetic recording medium is appropriately selected depending on the type and amount of the binder resin, ferromagnetic powder, etc. used. The amount added to the recording medium can be appropriately selected depending on the condition of the surface of the metal thin film, and is usually selected from the following range.

The content of the compound of the present invention is 0.1 to 3.0 g, preferably 1.5 to 2.5 g, per 100 parts by weight of ferromagnetic powder in the coated magnetic recording medium. In the case of a metal thin film type magnetic recording medium, 0 parts by weight per 100 parts by weight of the metal thin film.
．． The amount is 1 to 3.0 g, preferably 0.5 to 1.5 g.

If the amount used exceeds this range, the compound of the present invention will be present in excess on the surface, which may not only cause problems such as sticking and moisture absorption, but also cause damage to the magnetic layer when added to the magnetic layer. However, there is a problem in that the durability is actually lowered due to the action of plasticizing the binder and the like.

If the amount used is below this range, the surface amount will be insufficient and no effect will be obtained.

The compound of the present invention is not particularly limited, as long as it is a higher fatty acid ester having 24 or more carbon atoms, various conventionally known compounds can be used. That is, if the compound of the present invention is represented by a general formula, it can be represented by the following formula (1).

R'C00R2(I) In the formula, R1 is a hydrocarbon group having 14 to 35 carbon atoms, preferably an aliphatic hydrocarbon group, more preferably a straight-chain alkyl group, such as an octadecyl group or a hexadecyl group. , tetradecyl group, heptadecyl group, nanodecyl group, tetradecyl group, hexadecyl group, oftadecyl group, etc., R
2 is a hydrocarbon group having 4 to 30 carbon atoms, preferably an aliphatic hydrocarbon group, more preferably a branched alkyl group, such as an isohexyl group, an isohebutyl group, an isotridecyl group, a 2-ethylhexyl group, 2 -butyloctyl group,
2-hexyldecyl group, 2-octyldodecyl group, 2-
Decyltetradecyl group, etc., and R1 and R2 are R1 carbon number + 1 + R2 carbon number ≧24, preferably 35≧
It is appropriately selected based on the relationship: carbon number of R1+1+carbon number of R2≧24.

The cemented carbide material used in the present invention has a Mohs hardness of 7 to
Ten inorganic materials can be used, examples of which include tungsten carbide, titanium carbide, tank carbide, vanadium carbide, chromium carbide, silicon carbide, etc., with preference given to cobalt-containing tungsten carbide (tungsten carbide). On the other hand, Co5~
30 wtX, preferably 7 to 15-tχ), cobalt-containing tungsten carbide-titanium carbide, and the like.

In the present invention, the method for surface treatment of a magnetic layer using the superhard material includes applying a blade to the magnetic layer to treat the surface of the magnetic layer using a ferromagnetic powder, an abrasive, an antistatic agent, etc. In the case of metal thin film type magnetic recording media, blade methods, diamond wheels (rotary blades), etc. are used to cut protrusions of inorganic powder such as metal protrusions.

The blade is formed using a powder of the above-mentioned superhard material, preferably
Sintered particles having a particle size of 0.1 to 1.5 are preferred.

The cutting edge angle of the carbide material in the blade method is 5 to 18
When the magnetic recording medium is a tape, the cutting edge angle α of the superhard material 1 is 0.1 to 180 degrees, preferably 30 degrees, as shown in FIG. ~200
degree, more preferably 60 to 90 degrees, lamp angle β is 60 degrees
-170 degrees, preferably 80-170 degrees, ramp angle δ is 0-90 degrees, pressing force against the tape is 1-1
00g, tape tension T1 is 1 to 300g, preferably
50-250g, tape speed ν is 60-1200IIl
/111in, preferably 200-500m/m1n
(7) range is preferred.

The surface of the magnetic layer surface-treated with the superhard material in the present invention has an Ra value (Cut off value of 0.08 mm) 1
~15nm, preferably 1-10nm, microprotrusions are 1x103-1xlo9 pieces/m at 110-1O0n
Preferably, it is ff12.

Further, in the present invention, the surface roughness of the magnetic layer is preferably in the range of 5 to 10 nm in a coating type magnetic recording medium, and in the range of 1 to 6n++ in a metal thin film type magnetic recording medium.

The resin used for the magnetic layer of the coated magnetic recording medium of the present invention and the optional back layer (including the case of a metal thin film type magnetic recording medium) are conventionally known thermoplastic resins,
Thermosetting resins and reactive resins can be used.

For example, condensation resins such as polyester resins, polyurethane resins, cellulose resins, epoxy resins, polyamide resins, and phenolic resins, (meth)acrylic acid esters, styrene, acrylonitrile, butadiene, vinyl esters, acrylamide, vinyl chloride, and chloride. Polymers or copolymers such as vinylidene are available.

Furthermore, in order to improve durability, it is also possible to contain curable resins with various molecular weights, such as thermosetting resins such as polyisocyanate compounds and polyepoxy compounds, or low Molecular compounds (crosslinking agents, etc.)
There are also ultraviolet ray/electron beam curing reaction type resins and low molecular compounds (crosslinking agents, etc.) containing unsaturated double bonds.

Examples of polyisocyanate compounds include isocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and isophorone diisocyanate, products of the isocyanates and polyalcohols, and polyisocyanates produced by condensation of isocyanates. can be used. Commercially available product names of these polyisocyanates include Coronae) 2030, Millionate MR (manufactured by Nippon Polyurethane), Takenate D-102 (manufactured by Takeda Pharmaceutical), etc.
These can be used alone or in combination of two or more by taking advantage of the difference in curing reactivity.

In addition to the main functional groups, these thermoplastic resins, thermosetting resins, and reactive resins have functional groups such as carboxylic acid, sulfinic acid, sulfenic acid, sulfonic acid, sulfuric acid, phosphonic acid, phosphinic acid, boric acid, sulfuric acid ester groups, Acidic groups such as phosphoric acid ester groups and alkyl ester groups (these acidic groups may be in the form of Na salts, etc.) diamino acids, agonosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohols, alkyl betaine types, etc. Amphoteric group: can have amino groups, imino groups, imido groups, ado groups, epoxy groups, etc., or hydroxyl groups, alkoxyl groups, thiol groups, halogen groups, silyl groups, siloxane groups, and can be used as functional groups for various purposes. can be selected as appropriate.

The ferromagnetic powder used in the present invention includes 7-FezO,
, Co-containing Fe, Ol, 7-Fe, O.

, co-containing 7 Fe soa , Cr C)z ,
Various conventionally known ferromagnetic powders can be used, such as oxide-based fine powder such as hexagonal magnetobrambite ferrite, metal or alloy fine powder made of Fe, Co, Ni, etc.

The mixing ratio of the ferromagnetic powder and the binder in the magnetic layer is preferably in the range of 8 to 25 parts by weight based on 100 parts by weight of the ferromagnetic powder. If the amount of the binder is too small, the dispersibility and durability will be poor, and if the amount of the binder is too large, the degree of filling of the magnetic layer will be reduced, which is not preferable.

The magnetic layer of the magnetic recording medium of the present invention may further contain conventionally known lubricants, abrasives, and antistatic agents in addition to the compound of the present invention.

Examples of lubricants include silicone oil such as polysiloxane, carbon black, graphite, inorganic fine powder such as molybdenum disulfide, fine plastic powder such as polyethylene and polytetrafluoroethylene, higher fatty acids, and higher grade oils other than the compounds of the present invention. Examples include fatty acid esters and fluorocarbons.

These can be used alone or in combination.

The amount of these additives is 0.2 parts by weight per 100 parts by weight of the binder.
It is preferable to use it in a range of 20 parts by weight.

Examples of abrasives include non-magnetic inorganic powders with a Mohs hardness of 5 or more, preferably 6 or more, specifically aluminum oxides (α-alumina, γ-alumina, fused alumina, corundum, etc.), Chromium (Cr203),
Examples include oxides such as iron oxide (α-FetO:+), silicon dioxide, and titanium dioxide, carbides such as silicon carbide and titanium carbide, and fine powders such as diamond. The average particle size of these particles is preferably 0.05 to 1.0, and they can be added in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the ferromagnetic powder.

Examples of antistatic agents include carbon black (particularly preferred is one with an average particle size of 10 to 300+v), graphite, conductive powder such as carbon black graphite polymer, nonionic surfactants, anionic surfactants,
A cationic surfactant or the like is used.

The magnetic layer is formed by immersing and dissolving the above-mentioned ferromagnetic powder, binder, etc. in a solvent, dispersing it with a dispersion machine, and then coating it on a nonmagnetic support.

The solvent is preferably an organic solvent, including ketones such as methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as cellosolve and tetrahydrofuran, aromatic hydrocarbons such as toluene, and carbonized halides such as chloroform. Examples include solvents such as hydrogens.

For dispersion, various types of dispersion machines such as a sand mill can be used. For details, see "Pa1nt Flow and
Piga+ent Dispersion (Paint Flow and Pigment Dispersion)
The method described in John Wiley & Ring, published in 1964 by John Wiley & Ring, etc. can be used.

As a method for forming a magnetic layer on a non-magnetic support, conventionally known methods can be used, and in detail, the method described in the bottom of "Coating Engineering" (Asakura Shoten, 1970) etc. is used. be able to.

Further, the magnetic layer thus formed on the support is, if necessary, subjected to treatment for orienting the ferromagnetic powder in the magnetic layer, then dried, and subjected to surface treatment such as calendering treatment.

The surface treatment of the superhard material in the present invention is preferably carried out after calendering treatment.

The thickness of the magnetic layer is preferably 1 to 64 μm, preferably 2 to 5 μm.

In the present invention, the ferromagnetic metal used in the metal thin film magnetic recording medium includes iron, cobalt, nickel, other ferromagnetic metals, or alloys thereof, such as Co
-Ni5Fe-Co, Fe-Co-Ni, C.

-Ni-P and the like.

These ferromagnetic metals can be coated onto a non-magnetic support by methods such as electroplating, electroless plating, gas phase plating, sputtering, and ion blating to a film thickness of 0°02-211, particularly 0.05-211. It is set within the range of −.

Electromagnetic conversion characteristics and durability can be improved by introducing oxygen into the various ferromagnetic metal thin films described above, for example, by vapor deposition in an oxygen stream when forming the metal thin film. In addition to oxygen, N, Cr, Ga, As5
Sr, Zr, Nb.

Mo, Rh, Pd, Sn, Sb, Te, Pm, Re, O
s, Ir, Au, Hg, Pb5Bi, etc.

When the compound of the present invention is top coated on the metal thin film, the surface of the metal thin film can be modified with a surfactant such as a fatty acid or various coupling agents before providing the top coat layer. Moreover, this top coat layer may be one layer or may consist of a plurality of layers. Note that the above-described modification treatment, top coat layer structure, etc. can also be applied to coated magnetic recording media.

The surface treatment of the superhard material in the present invention is preferably carried out before the top coat treatment, after the magnetic layer is formed, or after the top coat treatment.

The thickness of the nonmagnetic support is preferably 4 to 50 μm.

Further, an underlayer may be provided on the support in order to improve the adhesion and magnetic properties of the ferromagnetic thin film.

In order to improve running durability, it is effective to provide minute protrusions on the surface of the support before forming the metal thin film (resulting in providing appropriate irregularities on the surface of the magnetic layer). Preferably, the density of the microprotrusions is 2×10 h to 2×10”/peng 2, and the height of one protrusion is 1 to 50 nm (nm: nanometer = 10 −9 meters).

Substrates used in coated magnetic recording media and metal fjtWi, type magnetic recording media include plastics such as polyethylene terephthalate, polyimide, boria, polyvinyl chloride, cellulose triacetate, polycarbonate, polyethylene naphthalate, and polyphenylene sulfide. A base, AI, Ti, stainless steel, etc. are used.

The magnetic recording medium may have any shape such as tape, sheet, card, or disk, but tape and disk shapes are particularly preferred.

〔Effect of the invention〕

The present invention includes a magnetic layer containing an existing higher fatty acid ester having 24 or more carbon atoms as a compound of the present invention, and
By surface-treating the magnetic layer with a superhard material, dropouts are reduced and head wear is suppressed.
The S/N ratio can be improved, and the cost of the magnetic recording medium can also be reduced.

〔Example〕

The present invention will be explained in more detail below using Examples. It will be readily understood by those skilled in the art that the ingredients, proportions, order of operations, etc. shown herein may be modified without departing from the spirit of the invention.

Therefore, the invention should not be limited to the examples below. In addition, parts in Examples and Comparative Examples indicate parts by weight.

[Example 1] After putting the following magnetic layer composition (1) into a kneader and thoroughly kneading it, (II) was additionally added, and after mixing and dispersing, (1) was added and dispersed to prepare a magnetic coating liquid.

Magnetic layer composition (I) Co-containing 1-Fe, 03 powder 10
0 parts (Nitrogen adsorption specific surface area 50rrr/g, powder Hc=7500e) Carbon black 6 parts (Asahi Carbon■
Polyurethane resin 6 parts (Toyobo MII, UR8600) Oleic acid 0.5 parts Methyl ethyl ketone 48 parts [11] Abrasive
1 part (manufactured by Shido Kagaku Co., Ltd., 8KP20) Polyurethane resin 2 parts (manufactured by Dainippon Ink Co., Ltd., C7209) Methyl ethyl ketone
20 parts [1 [1] polyisocyanate
8 parts (manufactured by Nippon Polyurethane ■, Coronate 3040) Myristic acid 1 part Fatty acid acid ester (Table 1, 1) Part X: Methyl ethyl ketone
20 parts After adjusting the viscosity of this magnetic layer coating solution, the thickness was 1
4. The dry film thickness on polyethylene terephthalate of a is
It is coated at a pressure of 5.0 - and dried while being oriented in the direction of coating progress using opposing magnets of 3000 gauss. Thereafter, the magnetic layer was continuously calendered, and then the following back composition [I] was mixed and dispersed in a ball mill on the back side of the non-magnetic support provided with the magnetic layer, and then [■] was added and mixed and stirred. Adjust the backing liquid and form a backing layer with a dry thickness of 0.5-.
After slitting to 0.5 inches, as shown in Fig. 1, a tungsten carbide material 1 (particle size 0°5-1 Co content 10 wtX) with a cutting edge angle α of 60 degrees was used to adjust the lap angle. β is 90 degrees, wrap angle δ is 15 degrees, pressing force against the tape is 5 g, and tape tension T.

The magnetic layer was surface-treated under the conditions of 110g of tape and a tape speed of 360o+/+++in, and 250g was placed on a VHS reel.
-I got involved.

Back layer composition (1) 100 parts of carbon black (manufactured by Cabot ■, C72 in Palcan) nitrocellulose (
Daicel) 5 parts Polyurethane polycarbonate resin (Dainichiseika, FJ2) 45 parts Phenoxy resin 15 parts (Union Carbide, PKHH) Methyl ethyl ketone 3
00 parts (U) polyisoyanene) 20
Part (manufactured by Nippon Polyurethane, C3040) Abrasive
0.3 parts (manufactured by Shido Kagakusha, former TL
oO) Lubricant (manufactured by Shin-Etsu Chemical, KF69) 0.1 part Copper oleate 0.1 part Methyl ethyl ketone 700 parts [Examples 2 to 6, Comparative Examples 1 to 3] In Example 1, the type and amount of fatty acid ester Samples were prepared in the same manner as in Example 1, with the changes shown in Table 1, and their performances were evaluated. The results are shown in Table 1.

Evaluation method (1) Dropout (D, O): 6 copies °
C190χRH After storage for 11 weeks, 15μsec, -
A dropout of 16 dB, 1 m1n, was measured.

(2) Head wear = After running for 50 hours at 25°C and 170χRH (7) The hide (-) of the VTR head was measured.

(3) Y S/N: Y S/N for VHS VTR
was measured.

(4) YS/N deterioration: YS/N was measured after repeated running at 20"C, 10XRH, and the deteriorated bone from the first bus was displayed.

As shown in Table 1, Examples containing the compound of the present invention and surface-treated with the superhard material according to the present invention are examples in which the superhard material is Compared to Comparative Examples 1 and 2, in which no surface treatment was performed using the compound of the present invention, and Comparative Example 3, in which no surface treatment was performed using a superhard material using the compound of the present invention, dropout and head wear were reduced, and Y S/ It can be seen that N and Y S/N deterioration is excellent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining the blade method, which is one of the surface treatment methods using a superhard material used in the present invention. Explanation of symbols l: Carbide material α: Cutting edge angle β, δ; Ramp angle T1: Tension procedure amendment figure January 28, 1991

Claims (2)

[Claims] (1) A magnetic recording medium having a magnetic layer provided on a non-magnetic support, wherein the magnetic layer contains a higher fatty acid ester having 24 or more carbon atoms and is surface-treated with a superhard material. A magnetic recording medium characterized by: (2) In a method for producing a magnetic recording medium in which a magnetic layer is provided on a non-magnetic support, a higher fatty acid ester having a carbon number of 24 or more is contained during and/or after the formation of the magnetic layer on the non-magnetic support. A method for producing a magnetic recording medium, which comprises: treating the surface of the magnetic layer with a superhard material after containing or not containing the higher fatty acid ester, or containing the higher fatty acid ester in the magnetic layer after the surface treatment. .